Furnish services, qualified personnel, material, equipment, and facilities not otherwise provided by the Government under the terms of this contract as needed to perform the techniques of quantum chemistry, to continue in-depth studies of polycyclic aromatic hydrocarbons and their methyl and amino derivatives that will parallel experimental efforts currently being made to help further elucidate their mechanism of transformation to activated and detoxified forms, and to characterize the interactions of their active forms with nucleic acid bases. Such studies will also be made for selected nitrosamides, nitrosamines, triazenes, aflatoxins, flavonoids, halogenated hydrocarbons, and directly acting alkylating agents. With the aid of mechanistic studies, parameters will be identified which should correlate to mutagenic and carcinogenic activity within each class.